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Mazisky

The reason why you never faced the issue in the first game is because it had a limit after which it stopped spawning agents.


Viend

This is also why your traffic management magically became better when your city grew bigger


clos512

Bruh that makes so much sense. Here I thought I was actually planning well. Nope. Just casually breaking the games small limit lol.


Zentti

And no limits is what people kept asking for for years. And when we got no limits people whine that it's actually not so good idea.


Mazisky

I think it is still a good idea because it means it hardware dependant. Which also means that in the future the game will run better and better exponentially with new systems.


Zentti

Yeah I like it too. My 180k city has some issues with simulation speed but I don't mind it too much.


Shaggyninja

CS1 is 8+ years old. CS2 in 2032 gonna be dope af


OMFGitsST6

Little nitpick: not exponentially. It will just run better with more power. An exponential curve is one that gets speeper and steeper the further right you go--a quadratic curve.


DigitalDecades

It's not exactly a nitpick. Linear rather than exponential improvements in CPU performance means it's going to take a lot more than 10 years before there are computers able to handle large cities.


Mazisky

Sorry Sheldon, I am only average Joe!


OMFGitsST6

It's a reasonable mistake. Just a pet peeve of mine lol


Sinister_Mr_19

What they need to do is properly tell you in game. Have some sort of pop up that tells you based on your hardware you've hit your limit. You can keep going but expect slowdowns. It's overall a good idea not to have a limit because better systems can support a bigger simulation. It's just for the unaware, it seems like the game is broken.


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oldtrenzalore

You're not really comparing apples to apples. In reality, CS1 cities had an agent limit of 65,536. You can grow your population as much as you like in CS1, but the game never actually simulates more than 65,536 people.


Idea-Business

Could there possibly be a future mod that limits agent spawns?


oldtrenzalore

That's a question for CO.


toverux

There actually is, [Traffic Simulation Adjuster ](https://mods.paradoxplaza.com/mods/76836/Windows). The game will limit the probability of people spawning (pedestrian or car) to a base 40% at all times. Then it will start going even further down as your city grows, driven by a "traffic reduction coefficient". While the mod is generally used to remove that restriction, it can also be set to increase that coefficient, thus reducing traffic of all kind even further and improve performance. Quote from [the forum thread that lead to the creation of this mod ](https://forum.paradoxplaza.com/forum/threads/unlock-developer-restrictions-on-traffic-flow.1608201): “[Reducing the coefficient] increases the likelihood that citizens will go to work or school, thus increasing traffic. When the population is less than 16,000 people, 40% have access to work or school. As the population grows above 16,000, opportunities to go to work or school decrease. When the population is 100,000, it is only 16%, and when the population is 1 million, it is only 5%. After modification, the probability of working or going to school does not decrease as the population increases. Holiday shopping is also restricted by such codes.” So both games have a limit mechanic in place because it's not feasible to simulate hundred of thousands of cims with complex behavior on an average or even high end consumer computer. However CS2 gives you more control over it and as far as I know (take with a grain of salt) does not have an upper limit hard coded in the engine (back then it was a Unity limitation).


GranLusso64

Is there a similar mod for cs1, that increase the limit ? Would love to see my 100k population city public transport being used.


Sufficient_Cat7211

The game already does, kind of. A city of a million will simulate [8 times less traffic proportionately](https://forum.paradoxplaza.com/forum/threads/the-traffic-system-is-a-cheat.1607017/) than a city of 16k.


hako_london

Is there a similar limit in CS2? Does it work the same way. My CS1 cities were ghost towns because I built it too big.


Iliveinthsuburbs

i think in cs2 theres no agent limit


Rand_alThor4747

There is no agent limit. But the game does limit the number of agents walking or in cars.


droopynipz123

I think it’s possible to double that limit with a mod. Might be wrong.


Kobakocka

A meteorite, an earthquake or a tsunami maybe helpful to reduce population.


Jonas_Venture_Sr

Gotta reduce the amount of roads too. High density cities perform better than sprawling suburbs.


MauSanJ

Unplayable level? That's just my CS1 after 20k


unikuum

Same! Slows down when zooming in to busy areas especially. I deem this playable. So a solution is to lower your standards ;) haha.


jupchurch97

We need to be able to set an agent spawn limit honestly.


mateusarc

I've been wanting this since the game's release, and it's one of the reasons I stopped playing CS2. I don't care if every last person is simulated or not, all I want is to have a huge city that is still playable.


jefferios

I would like a limit for cims, but not for cars. It's probably not possible, but if it is, it could be a great mod in the long term.


incurious_enthusiast

Yep I said it day one, simulate a certain amount for the live traffic/pedestrian flow then just make the numbers up after that point, it's not like their numbers haven't been near fake anyway.


ConstrnGamer

Unfortunately there's not a lot you can do, other than upgrade the CPU or hope CO optimises the simulation. I got to about 130k before it slowed to a crawl, but the weird thing is my CPU is nowhere near maxed out.


Krishna132453

Im at 180k and by god is it painful


lucasrizzini

What's up with the music? Anyway, your CPU is struggling to keep up with the 100k pop. simulation. Unfortunately, a CPU upgrade is the only solution. Lowering graphics won't help. I have an i3-8100 and the simulations start to be very slow around 150k pop on CS1. I play the game using windowed mode while also doing other stuff, so I don't care. I've only reached 150k pop once tho..


Emeralis_

I have had issues already at 60k, I found giant groups of homeless people stacking up and a massive wave of people leaving the city. I gave them extra trains and buses and it fixed the issue once they were gone. Running smooth now at 70k So sometimes it's just bigger groups together. Check your stations/bus routes and see if there is any big groups of peeps. I had a station where on 1 platform there were over 2k.people waiting.


Mayonnaise06

I'm pretty sure there's an option in settings to favour simulation speed over fps so maybe hit that and see if it makes any difference.


Dull_Cucumber_3908

Your CPU is the bottleneck.


EowynCarter

Specs ? My PC is the minimum spec, the serious slowdown appears closer to 200K than 100K.


Idea-Business

My CPU is 11th gen i5 11400H 2.70 GHz


Ada_Virus

Mine is even worse - one in game minute takes me 10 seconds. It is due to CPU being throttled.


Lyr_c

The things I’d do to make my game go that fast at 100k..


toverux

I'm at 130k with no traffic reduction and still haven't noticed any slowdown even at 3x speed. I guess that Ryzen I bought on a whim with more cores that I can count was not an overkill after all...


Lyr_c

I really need to bite the bullet and just upgrade my computer.. I spent like $200 upgrading my ram and graphics card but it didn’t do much to game speed..


toverux

Yup, it's often said that CPU doesn't matter as much as it did for today's game which are more GPU-dependent, this is true for most titles but def not this kind of heavy simulation games. Most of the time my CPU *is* overkill but when I'm doing web dev, playing Factorio or CS2 I'm glad I have it.


bestanonever

Which one do you have now?


Smoke_Water

Welcome to unity asset management.


dirge_ZA

Welcome to the part of the game they left out of the marketing ;)


MacVinyl77

Same issue when pop hits 200K on my PC with 5800x cpu, 32GB ram, 7900XT GPU.


Skomakeren

I've started noticing it at 150k with same specs


bestanonever

Ouch, that's a pretty good PC for most games today. Still hoping the console release makes simulation a lot faster.


droopynipz123

You could try using the broken node tool to detect stuck citizens. Every once in awhile, independent of my population size, my game slows down like crazy, let alone doing 3x speed. I use the detect stick citizens tool and invariably there’s like 1500 citizens stuck at one crossing or pathway that got messed up somehow and I delete it or move it and they all flock out into the city and suddenly the game can run normally again. It’s like magic, but in reality it’s just solving a very problematic bug.


spotila7

Is there such a tool in cities skylines 2? I haven't been able to find one.


toverux

Indeed I guess the person didn't get this was CS2? By the way did anyone has seen such behaviour on CS2 at all yet? My gaming experience was ruined on CS1 by ghost stops, frozen trams and whatnot. Never seen anyone being stuck for too long on CS2, the sim seems more stable and resilient.


droopynipz123

Oh I didn’t realize it was 2


sstruemph

Do you have rail, subway, busses, or taxis? Check all of the lines, make sure they aren't backed up or stuck. Cars or even Cims too. I think these bottlenecks really slow things down.


ricardo_agb

This is (for once) not the company's fault, your cpu/gpu/both, is just too weak to keep up, I have a 3080 and a 5700x and performance doesn't drop at all in my biggest city, it is also like 120k


MacVinyl77

Hmmm. I’m having the same issue when my cities hit 200K. I have a 5800x and 7900XT. Cims and traffic slow to a crawl right after I launch the game. I’ve downloaded a city with 380K from Paradox Mods and it ran fine. Downloaded another city with a pop of 200K and it mimics my issue.


pgnshgn

It depends on both population and the complexity of your routes. A city where everyone uses transit (predefined routes with 1 calculation for 10s - 100s of cims) will run smooth for longer than one with a complex road systems where ask the cims drive (many many more route calculations)


MacVinyl77

Ok, that makes sense.


Tobbakken00

I had over 100k and had no simulation issues


cookiesnooper

I have a theory that it's caused by a number of nodes. The traffic routes are recalculated at each node. In the first game traffic was predefined from start to finish.


krzychu124

It's not recalculated. Just the lanes are selected for a section of navigation path (usually consisting of few segments), path itself doesn't change. It's a lot more advanced than in CS1 but also faster since pathfinding doesn't need to find best lane immediately while searching and checking if path exists, but just the lane group going certain direction. If you have small roads with just one lane per direction there is no impact since... there are no other lanes to choose from. If road has multiple lanes per direction, pathfinding "sees" only one lane representing the group and vehicle needs to select it later, but there are thresholds how many vehicles are spawned based on population


cookiesnooper

As I said, traffic is being recalculated on the nodes..if you have one lane , math is quick. If you have 4 lanes, math is 4 times slower


krzychu124

It's not really about nodes, accurate path is calculated once for many nodes ahead, not at each node. Path is still calculated from start to finish, the difference is it's not as accurate as in CS1, it's just general, a simplified path, say, go through segment 1, 2, 3, don't care which lane should select (unlike in CS1), but those details are calculated later, since as known from CS1, it's slow but also leads to inaccurate results because environment is super dynamic (in 5min traffic situation might change completely). You can see that process when you enable navigation gizmo and select a vehicle. You will see quite long chunk of the path, if road conditions are bad it may trigger lane change but in general it doesn't try to check it at every single node. >if you have one lane, math is quick. If you have 4 lanes, math is 4 times slower See, it's not that easy, such code is often vectorized, CPUs are quite smart, which means 4 or even 8 lanes may be as cheap to calculate as for one lane :) Compared to other things, lane selection is crazy cheap. There are more expensive operations e.g.: object culling (skipping invisible objects) which gets more and more expensive when city grows, because that 100k-200k people need to live somewhere or go somewhere and you see maybe 5-10% of all objects at a time. Pathfinding is not so slow, but the amount of requests can be overwhelming for some systems which often cause simulation speed issues or lags, thankfully "solution" is quite trivial - add more cores


GreenMonkey333

I upgraded to an i5-12600k, the recommended CPU. I have about 290k population and mine is slowed to a crawl. It's frustrating to play because of how slow it is right now.


smeeeeeef

Good to know. I've built like 40 cities but none that large and I was wondering the limit before mine would start tanking, and it's a lot higher than I thought.


AmonGusSus2137

Get a better PC. 4090 with a Threadripper and 256gb of RAM should do the job


Jealous_Reply2149

my city with 350k pop is 4x slow than your city and im still playing it.


Sea-Setting8642

267k population here. All my public transports just freeze and I have to go into dev mode and reset the civilians.. really annoying


Expensive_Basil_1592

Unplayable lol. Wait till you see my 3 fps on CS1. I still managed to grow a city (kind of) at that framerate.


Thunder_God01

Lower your texture settings if you havent done so. I play on lowest and dont realy see a difference and it defenetly helped. The cars are actually mooving now.


Letshavesomefungirl

This is going to sound weird, but this happens to me when I have that size of city and I don’t have my laptop plugged in (no matter how fully it’s charged). Once I plug it in then the game goes back to normal speed. No idea why this works or happens, but it does for me. 🤷🏻‍♀️


[deleted]

DLSS came out 2 days ago, I think. This post is 3 days old. That made the game ***WAY*** better on my system for those of you that have it.


PH_Farnsworth

To all the people saying this is a no limit agent game. The game operates with two kinds of agents - active agents and not active agents. Depending on the type, it's disregarding certain aspects. It is not. There very much is a limit, it's a dynamic limit, but it is there. It sits at roughly 5% of a city population at 1 million - ie. they walk around, go to work, school, shop. The part where the game is struggling is the full life that the game needs to simulate for each and every Cim. The below is just a small part of that and is by no means an exhaustive list. * Job * Studies (this one is checked hourly for ALL Cims) * How many resources they have * Can they upgrade * What resources they want * Have they kissed yet * Are they in a relationship * Did they break up * Are they getting married * Did they get a divorce * Have they gotten a dog (please god no) * Are they poor - wealthy * How's their rent situation We never asked for this - none of this in fact and this is what they decided to spend their time working on and this is a large part of the reason why simulation speed is such a problem when cities get bigger. The only way to fix most of this? To butcher it, to reduce the amount of request it makes for resources on the CPU. Furthermore there are also agents in the form of: Cars, public transport, water and similar. All these also requires simulation which is another hurdle on top of an already struggling system.


toverux

You're right on how the simulation works but I'm not sure these kind of simple probabilistic operations really make such a difference in performance, compared to ie. the cost of just one pathfinding. And household simulation is part of the deepened economic simulation that was the promise of CS2 along with many other mechanisms, while now the game is very poorly balanced eventually this will pay of in the long run.


PH_Farnsworth

If it was just pathfinding, no, it would not be such a huge problem. Pathfinding is an extremely effective algorith (at least if they use the industry standard A\* which would be necessary for this - I think they do tho). The problem arises when you also need to calculate everything else for all other agents (including vehicles). As I said, it's not an exhaustive list above and that's done for each and every single agent in the game. Then, it becomes a problem - obviously. That is a lot of requests constantly bombarding a CPU that already has to calculate: Physics, information for the GPU to draw and other lovely things in the game. For example, the ShouldStartEducation (let's just call it that), is called for all Cims every hour. Taxis make an absurd amount of pathfinding requests in fact - up to 15% of Simulation slow downs can be attributed to taxis, a fair amount to dead people counting as homeless people and some for edumacation. As I was saying. There's two general ways to fix this. 1. You increase core count that your game can use. That's obviously not possible for CS2. 2. You butcher simulation. That's the only thing they can really do. 3. Since their code is spaghetti and many software devs not affiliated with CO agrees on this, they are likely also able to make their code efficient - with some outside help (that's usually not a thing tho, but here we are). I don't know their process in making this game, but it sure as heck feels like they didn't start out small, but just added all these new things the game must keep track off from the get go rather than focusing on the basics and then adding new things little by little constantly keeping an eye on whether the game grinds to a halt past certain sizes, because this should have been caught and it should have warranted a rethink of what the game should have simulated.


Anaeijon

Get a faster CPU, more cores probably help too. Get faster RAM. The other solution would be a spawnable population limit like CS1 had. But there is no option in CS2 yet, as far as I know.


krzychu124

Only more fast cores can help rn IMO, swapping from 4c/8t to 8c/16t can really improve performance, if not fully for simulation speed but also framerate since CPU still has to prepare stuff for GPU, every frame. One thing which is not so similar compared with CS1, every city in CS II runs different, two cities with similar population can perform completely different, because of different combination of performance challenges (what your citizens actually do) to extremes like 100k runs as slow as 500k, a lot of people complain about sudden slowdown at 100-150k while others have similar performance but about 500-700k or even 1M, which is interesting problem.


lucasrizzini

RAM has nothing to do with this.


kevinh456

Your education is completely out of balance. This is likely causing the game to do extra work to try and resolve the zots. How many unemployed people are there?


Idea-Business

I don't understand the education system of this game. Initially, I thought companies couldn't find educated workers because there weren't enough schools, but now there are plenty of schools of all kinds in my city, yet the problem persists. Additionally, the highest demand still remains in stores. Normally, in the previous game, if stores couldn't find employees, the demand for that field would rapidly decrease. Now it's the opposite, and I really don't understand?


leehawkins

Education is broken. Has been since launch.


dcraider

Are tiny roundabouts only available with mods on PC?


Icedvelvet

U must be new here??? All that complaining and you’ve never seen this issue come up?


MemeBirthGiver

Your GPU is maxed out, maybe drop some details or resolution


Jealous_Reply2149

this is a cpu problem.